The thumb reference explains an obvious way to identify anyone who makes
a living working on automobiles. Automechanics typically have black
grease under the finger and thumb nails. In addtion, the thumb has a
tendency to take some abuse in this occupation, and after a while will
have a hammered on appearance. Sir Arthur Conan Doyle would be proud.

From: jsuder@moose.uvm.edu (Jane P. Suder)

Speaking from personal experience? I think the grease thing is not
exactly right, although they do have dem greeeesy fingerz.... but the
hammered thumb thing might be it.....

From: linetramp@delphi.com

As a general rule, the thumbs and fingers of mechanics are noticably
scarred and calloused from working with cast iron and stamped steel. A
seemingly permanent black stain from the carbon in grease and oil is also
common in that line of work. In addition, mechanics are seldom regarded
as members of the intellectual elite, so the stigma of a black, scarred
thumb could translate to "destined for a lifetime of failure and
mediocrity". i.e. "Wind up working in a gas station"...

Hey now, better make a decision.
Be a moron, and keep your position.
You oughta know now, all your education,
won't help you no-how.

From: Evil Bob <evilbob@tbag.tscs.com>

In this sentence it is used in the sense of "anyhow" or "anyway".
Many uneducated people in this country use the phrase "no-how" instead of
"anyhow" or "anyway" as in the phrase "I don't care if the library
burned down - I never went there no-how".